JP5036282B2 - IMAGING DEVICE, FOCUS ADJUSTMENT METHOD FOR IMAGING DEVICE, AND ENDOSCOPE DEVICE - Google Patents

Description

  The present invention relates to an imaging apparatus for observing a subject, a focus adjustment method for the imaging apparatus, and an endoscope apparatus including the imaging apparatus.

An imaging device is incorporated in the insertion portion of the endoscope device, and it is possible to observe a subject positioned forward or sideward on the distal end side of the insertion portion by this imaging device. Such an imaging apparatus is provided with an autofocus function, which makes it possible to appropriately observe the subject even if the distance to the subject changes. As a specific configuration for providing the autofocus function of the imaging apparatus, for example, an imaging element, a movable member that moves the imaging element in the optical axis direction of the objective lens, and the imaging element in the optical axis direction of the objective lens are 10 kHz. 2. Description of the Related Art An imaging apparatus including a piezoelectric element that vibrates at a certain frequency and an extraction unit that extracts a frequency component that is the same as the frequency of the piezoelectric element in a video signal output from the imaging element has been proposed (for example, Patent Documents) 1). According to this imaging apparatus, when the imaging element is located at the focus position, the video signal having the frequency component is not detected by the extraction unit. For this reason, when the video signal is detected by the extraction means, the image pickup device is moved to a position where it can no longer be detected by moving the image pickup device with the movable member, so that the image pickup device is placed at the focus position and is always in focus. An image can be output.
Japanese Patent No. 2732462

  However, according to the imaging device of Patent Document 1, the imaging element always vibrates in the optical axis direction of the objective lens at a frequency of about 10 kHz by the piezo element, that is, the relative positional relationship between the imaging element and the objective lens is: It always fluctuates with the above frequency and a predetermined amplitude. For this reason, the focus of the optical image formed on the image sensor changes according to the vibration of the image sensor, and as a result, the resolution of the video obtained by continuously acquiring images by the image sensor decreases. There was a problem. In addition, based on the result detected by the extraction means, the position of the image sensor is constantly moved, that is, focused so that a video signal having the same frequency component as the vibration of the piezo element is not detected. As a result, the image was difficult to see for the observer. As a countermeasure, it is conceivable that the autofocus function provided in the image pickup apparatus can be switched on / off by a switch. However, manually switching the presence / absence of the autofocus function defeats the original purpose and is an unnecessary operation. Increases and the observation work becomes complicated.

  The present invention has been made in view of the above-described circumstances. Normally, an image is output with a substantially constant focus. On the other hand, when observing a subject, the output image is optimally focused. An imaging apparatus capable of observing a subject with a high-resolution image, a focus adjustment method for the imaging apparatus, and an endoscope apparatus including the imaging apparatus are provided. is there.

In order to solve the above problems, the present invention proposes the following means.
An imaging apparatus according to the present invention includes an objective lens, an imaging element that is arranged coaxially with the optical axis of the objective lens, receives incident light collected by the objective lens, and repeatedly acquires images, and the imaging device The image sensor moving means for moving the element on the optical axis of the objective lens is compared with the image acquired this time with the image sensor and the image acquired last time. If not, a control unit that adjusts the position of the image sensor to the focus position by the image sensor moving means, and a focus area as a partial range in the image acquired by the image sensor in advance. set, and an adjustable operating section the position of the center of the focus area within the image, wherein the control unit includes a contrast value detecting means for detecting a contrast value of the image, the The position of the imaging element is adjusted by the imaging element moving means to a position where the contrast value of the image detected by the contrast value detecting means is maximized, and the imaging is performed based on the contrast value in the focus area. A control unit that adjusts the position of the element, and the control unit of the control unit has a position of the imaging element when the contrast value is maximized when the focus area is designated by the operation unit. And measuring the center position of the focus area on the image and designating it as the center position of the focus area based on the measured position of the image sensor and the center position of the focus area on the screen The calculated actual three-dimensional coordinates can be calculated, and the control unit The image is compared with the previously acquired image, and the presence or absence of a change from the previously acquired image of the image acquired this time is determined by the luminance signal in each image. If not, the image acquired last time is compared with the image acquired last time, and the presence or absence of a change from the image acquired last time according to the luminance signal in each image from the image acquired last time And when the image has changed in comparison with the previous image, the image pickup device moving means adjusts the position of the image pickup device to be the focus position . .

The present invention also includes an objective lens, and an imaging device that is arranged so as to be movable back and forth on the same axis as the optical axis of the objective lens, and that receives incident light collected by the objective lens and repeatedly acquires images. A focus adjustment method of an imaging apparatus comprising: a focus area is set in advance as a partial range of the image acquired by the imaging device; a center position of the focus area is adjusted in the image; A contrast value in the focus area of the image acquired by the image sensor is detected, the image acquired this time by the image sensor and the image acquired last time are compared, and a luminance signal in each image is used. determine the presence or absence of a change from the image obtained in the previous time this time the acquired image, if the image is not changed before and after, on the optical axis of the image pickup element and said objective lens So moved, adjusted to focus position a position of the imaging element, wherein by comparing the currently obtained the image and the image obtained in the previous time by the image pickup device, the image is not changed before and after If not, the image acquired last time is compared with the image acquired last time, and the presence or absence of a change from the image acquired last time according to the luminance signal in each image from the image acquired last time When the image has changed in comparison with the previous image, the position where the contrast value is maximized is measured based on the contrast value in the focus area. Actual three-dimensional coordinates designated as the center position of the focus area based on the position of the image sensor and the center position of the focus area on the screen Calculated, by adjusting the position of the imaging element so that the focus position, and wherein adjusting the position of the imaging element.

  According to the image pickup apparatus and the focus adjustment method of the image pickup apparatus according to the present invention, the position of the image pickup element is moved on the optical axis of the objective lens by driving the image pickup element moving unit by the control unit. The focus of the image can be adjusted. Here, the control unit determines whether or not to adjust the position of the image sensor based on whether or not the repeatedly acquired image has changed between the current time and the previous time. That is, when the relative position of the objective lens is changed with respect to the subject, for example, to search for the subject to be observed or to adjust the distance from the subject to be observed, the information is repeatedly acquired. The image changes before and after, and the control unit does not adjust the position of the image sensor based on the change in the image. For this reason, the observer searches for a subject to be suitably observed based on images continuously projected in a stable state although the focus is not in an optimal state, or the objective lens and the subject. And the distance can be adjusted.

  On the other hand, when the subject to be observed can be confirmed, the observer stops the objective lens, and the relative position of the objective lens with respect to the subject is constant. In this case, the repeatedly acquired image does not change before and after, and the control unit adjusts the position of the image sensor to the focus position based on the fact that there is no change in the image, so that the focus is in the optimum state. Can be. Since the position of the image sensor does not fluctuate unless the relative position of the objective lens with respect to the subject changes, the observer can preferably observe the subject with a high-resolution image. .

  Furthermore, according to the imaging apparatus and the focus adjustment method of the imaging apparatus according to the present invention, the contrast value detection unit of the control unit can detect the contrast value of the image acquired by the imaging element. Here, when the relative position of the objective lens with respect to the subject is constant, the contrast value of the acquired image becomes maximum when the focus is in an optimum state. That is, by adjusting the position of the image sensor so that the contrast value is maximized by the control unit of the control unit, the image sensor becomes the focus position, and an image is acquired with the focus in an optimum state to observe the subject. be able to.
  Furthermore, according to the imaging apparatus and the focus adjustment method of the imaging apparatus according to the present invention, the contrast in the focus area that is a limited range in the acquired image as to whether or not the focus is in an optimum state. Can be evaluated by value. For this reason, it is possible to focus on the subject displayed in the focus area in the image, and it is possible to preferably observe the subject in the focus area.

  Furthermore, according to the imaging apparatus and the focus adjustment method of the imaging apparatus according to the present invention, the center position of the focus area can be adjusted to the position that is particularly desired to be observed in the subject displayed as an image by the operation unit. For this reason, it is possible to preferably observe the subject in the designated focus area.
  Furthermore, according to the imaging apparatus according to the present invention, the control unit of the control unit can measure the position of the imaging element and the center position of the focus area on the image. Here, when the focus is in the focus area, the position of the image sensor and the center position of the focus area on the image and the actual three-dimensional coordinates specified as the center position of the focus area are correlated. It is in. For this reason, the three-dimensional coordinates of the center position of the focus area can be calculated from the measured position of the image sensor and the center position of the focus area on the image, that is, the image is displayed at the center position of the focus area. The position of a specific part on the subject can be measured.

  According to the imaging apparatus and the focus adjustment method of the imaging apparatus according to the present invention, the control unit can also perform the processing for the images acquired in the previous time and the previous time, when the repeatedly acquired images have not changed between the current time and the previous time. Make a comparison. Then, the position of the image sensor is adjusted when the previous image changes compared to the previous image. That is, when the relative position of the objective lens with respect to the subject has changed and is relatively stationary immediately before, the focus is adjusted to be in an optimum state, while the relatively stationary state continues. In this case, the position of the image sensor is not unnecessarily changed, and the observer can observe the subject with a more stable image.

  In the imaging apparatus, the control unit may detect the image based on luminance detection means for detecting the luminance of the image and whether the luminance of the image detected by the luminance detection means is correlated. It is more preferable to include a control unit that determines the presence or absence of the change and adjusts the position of the image sensor by the image sensor moving means.

  Further, in the focus adjustment of the imaging apparatus, the brightness of each image repeatedly acquired by the imaging device is detected, and whether or not the image has changed is determined based on whether or not the brightness of the image has a correlation. It is preferable to judge and adjust the position of the image sensor.

  According to the imaging apparatus and the focus adjustment method of the imaging apparatus according to the present invention, the luminance of the image acquired by the imaging element can be detected by the luminance detection unit of the control unit. Here, if the relative position of the objective lens with respect to the subject changes, the detected image changes, and the detected luminance also changes. Therefore, the control unit of the control unit can quantitatively determine the presence / absence of an image change based on the presence / absence of the luminance correlation, and can start the adjustment of the position of the image sensor.

  Furthermore, in the above-described imaging device, the control unit of the control unit is configured such that the distance L from the principal point of the objective lens at the position of the imaging element and the center position of the image at the center position of the focus area The two-dimensional coordinates Mx, My on the image with the origin as the origin are measured, and the three-dimensional coordinates X, Y, Z at the center position of the designated focus area with the principal point of the objective lens as the origin Is more preferably calculated from the formulas shown in <Equation 1>, <Equation 2>, and <Equation 3> (where the symbol f is the focal length of the objective lens).

  According to the imaging apparatus according to the present invention, the position of a specific portion on the subject displayed at the center position of the focus area is measured by the above <Equation 1>, <Equation 2>, and <Equation 3>. can do.

  In the imaging apparatus, the operation unit can specify a plurality of the center positions of the focus area in the image acquired by the imaging device, and the control unit of the control unit is calculated. Further, it is more preferable that an actual point-to-point distance between the center positions of the focus areas can be calculated based on the three-dimensional coordinates of the center positions of the focus areas.

  According to the imaging apparatus of the present invention, the center position of the plurality of focus areas can be designated by the operation unit, and the actual three-dimensional coordinates of the center position are calculated for each of the designated plurality of focus areas. Can do. Therefore, the actual distance between a plurality of points arbitrarily designated as the center position of the focus area can be measured on the subject displayed in the image.

  In the above imaging apparatus, the imaging element moving means is provided so as to be able to advance and retreat on the same axis as the optical axis of the objective lens, and a shaft body in which the imaging element is disposed at a tip, and the shaft body A cylindrical body disposed on the outer periphery of the proximal end, and either one of the shaft body and the cylindrical body is a permanent magnet that forms a magnetic field substantially parallel to the optical axis of the objective lens, and More preferably, the other of the shaft body and the cylindrical body is an electromagnet capable of forming a magnetic field substantially parallel to the optical axis of the objective lens.

  According to the imaging device of the present invention, when an AC voltage is applied to the electromagnet with one of the shaft body and the cylindrical body as a permanent magnet and the other as an electromagnet, a voltage having an equal absolute value is applied to the electromagnet. Since they are alternately applied symmetrically, the shaft body is stationary so that the base end of the shaft body is located at an intermediate position inside the cylinder. In addition, when a positive DC voltage is applied to the AC voltage in a superimposed manner, positive and negative voltages with different absolute values are alternately applied to the electromagnet in an asymmetrical manner. In accordance with the magnitude of the DC voltage, the base end of the shaft body moves to a position biased to one side rather than the intermediate position of the cylinder body. In addition, when a negative DC voltage is applied to the AC voltage in a superimposed manner, the base end of the shaft body moves to a position that is biased to the other side of the intermediate position of the cylinder. That is, by changing the magnitude of the DC voltage applied to the electromagnet of the image sensor moving means in a superimposed manner together with the AC voltage, the position of the image sensor disposed at the tip of the shaft body is changed to the optical axis of the objective lens. Can be adjusted above.

  Furthermore, in the above-described imaging device, it is more preferable that the control unit includes a voltage applying unit capable of applying an alternating voltage and a direct-current voltage whose magnitude is variable to the electromagnet in a superimposed manner. .

  According to the imaging apparatus of the present invention, the voltage application means of the control unit changes the magnitude of the DC voltage applied in a superimposed manner together with the AC voltage to the electromagnet of the imaging element moving means, thereby changing the axis of the imaging element moving means. The position of the image sensor provided at the tip of the body can be adjusted on the optical axis of the objective lens.

In addition, an endoscope apparatus according to the present invention includes the above-described imaging device, and an insertion portion in which the objective lens of the imaging device is provided on a distal end side and can be inserted into a subject.
According to the endoscope apparatus according to the present invention, when the insertion portion is inserted into the subject, the focus is not optimized but is stabilized by the control unit of the imaging apparatus. Can do. For this reason, it is possible to insert the insertion portion to the observation position while suitably confirming the subject by the acquired image. On the other hand, when observing the subject with the insertion portion inserted stationary, the control unit of the imaging apparatus can adjust the position of the imaging device to achieve the optimum focus, and the acquired high The subject can be preferably observed by the resolution image.

According to the image pickup apparatus of the present invention, the image pickup device moving means and the control unit are provided, so that the image is normally output with the focus being in a substantially constant state, while being output when the subject is observed. The subject can be observed with a high-resolution image by automatically adjusting the focus of the image to an optimum state.
In addition, according to the focus adjustment method of the imaging apparatus of the present invention, the image is usually projected with the focus substantially constant, and the image is adjusted so that the focus of the image is optimal when the subject is observed. The object can be observed with a high-resolution image.
In addition, according to the endoscope apparatus of the present invention, by including the above-described imaging apparatus, it can be inserted into the subject and the subject can be preferably observed.

  Hereinafter, an endoscope apparatus according to an embodiment of the present invention will be described with reference to the drawings. 1 to 5 show an endoscope apparatus 1 as an embodiment of the present invention. As shown in FIG. 1, an endoscope apparatus 1 includes an insertion part 2 that is inserted into a stenosis part or the like for observing a subject, an operation part 3 provided at the proximal end of the insertion part 2, and an insertion part. 2 and an imaging device 10 that images a subject located on the distal end side. The insertion portion 2 includes a hard distal end portion 4, a bendable bending portion 5, and a flexible flexible tube portion 6 in order from the distal end side to the proximal end side. When the flexible tube portion 6 is inserted into a narrowed portion or the like, the flexible tube portion 6 can be bent in accordance with the shape thereof, thereby enabling easy insertion of a subject to be observed. In addition, a bending mechanism (not shown) is built in the operation unit 3, the flexible tube unit 6, and the bending unit 5, and the bending unit 5 can be freely operated by operating the knob 3 a provided in the operation unit 3. Can be curved.

  As shown in FIGS. 2 to 4, the imaging apparatus 10 includes an objective lens 11 provided on the distal end surface of the distal end portion 4 of the insertion portion 2, an LED 12 that is an illumination unit, and an objective lens 11 inside the distal end portion 4. An image sensor 13 disposed coaxially with the optical axis L11, a monitor 14 for outputting an image acquired by the image sensor 13, and a control unit 15 are provided. The control unit 15 performs various controls and is connected to the operation unit 3 by a cable 15a as shown in FIG. Details of the control unit 15 will be described later. The imaging device 13 is a CCD, for example, and illuminates the subject with the LED 12, receives the incident light reflected and collected by the objective lens 11 at the light receiving surface 13a, and outputs a photoelectric conversion output PO that becomes a video signal. Can be output to the control unit 15.

  Further, the imaging apparatus 10 includes an imaging element moving unit 16 that moves the imaging element 13 on the optical axis L11 of the objective lens 11. More specifically, as shown in FIGS. 4 and 5, the imaging element moving unit 16 includes a shaft body 17 disposed coaxially with the optical axis L <b> 11 inside the distal end portion 4, and a proximal end of the shaft body 17. And a cylindrical body 18 covering the outer periphery of the 17a side. A fixing plate 19 is fixed to the tip 17b of the shaft body 17, and the image sensor 13 is fixed to the tip surface 19a. A guide 20 extends substantially parallel to the optical axis L11 at a position corresponding to the fixed plate 19 on the inner peripheral surface of the distal end portion 4, and fixes the fixed plate 19 so as to be able to advance and retreat. For this reason, the shaft body 17 and the image sensor 13 can be advanced and retracted on the optical axis L11 by the guide 20. In addition, the coil 21 is wound around the outer peripheral surface of the shaft body 17, and by supplying a current, an electromagnet that generates a magnetic field in the direction of the optical axis L11 can be obtained. On the other hand, the cylindrical body 18 is a permanent magnet capable of generating a magnetic field in the direction of the optical axis L11. For example, the cylindrical body 18 is fixed to the inner peripheral surface of the distal end portion 4 with the distal end 18a as the N pole and the proximal end 18b as the S pole. Has been. Then, by applying a predetermined voltage to the coil 21 by an electromagnet drive circuit 27 of the control unit 15 to be described later, a shaft is generated by the interaction between the magnetic field of the shaft body 17 serving as an electromagnet and the magnetic field of the cylinder body 18 serving as a permanent magnet. The body 17 can be moved to a predetermined position along the optical axis L11, whereby the position of the image sensor 13 on the optical axis L11 can be adjusted. Next, the control unit 15 will be described.

  As shown in FIG. 2, the control unit 15 is a CPU 22 that is a control unit, a power supply circuit 23, an image sensor driving circuit 24, a video signal processing circuit 25, a contrast value detection unit 26, and a voltage application unit. An electromagnet driving circuit 27, a ROM 28, and a RAM 29 are provided. Details of each component will be described below. The power supply circuit 23 can supply power to the LED 12 to cause the LED 12 to emit light, and also supplies power to other components of the control unit 15 to drive it. The image sensor driving circuit 24 can output a drive signal DS necessary for driving the image sensor 13 to drive the image sensor 13. The image sensor driving circuit 24 outputs the pixel clock signal CK, the horizontal synchronizing signal HD, and the vertical synchronizing signal VD simultaneously with outputting the driving signal DS, and transmits them to the CPU 22 and the video signal processing circuit 25, respectively. The pixel clock signal CK can also be transmitted to two AD converters 30 and 33 described later.

  The video signal processing circuit 25 is connected to the image sensor 13 and outputs a photoelectric conversion output PO that is a signal for each pixel input from the image sensor 13 as a video signal VS such as a general NTSC signal. It is possible. The output video signal VS is input to the monitor 14 via a focus area overlay circuit 38, which will be described later, and the observer can observe the subject using images continuously displayed on the monitor 14. Further, the video signal processing circuit 25 can output a luminance signal BS corresponding to only the luminance portion of the video signal VS based on the photoelectric conversion output PO input from the image sensor 13 as luminance detection means. It is. The output luminance signal BS is input to the AD converter 30, is AD converted, is input to the CPU 22, and is also input to the contrast value detection means 26.

  The contrast value detection means 26 includes a high pass filter (HPF) 31 and a detection circuit 32. The high-pass filter 31 is connected to the video signal processing circuit 25 and passes a high-frequency component in the output luminance signal BS. For example, only the frequency component of 1 MHz or higher is passed. In addition, the detection circuit 32 can output a contrast signal CS that is an output signal indicating a positive envelope for the waveform of the high-frequency component of the luminance signal BS output from the high-pass filter 31. FIG. 6 shows an example of the luminance signal BS in the 1H period (a period corresponding to one horizontal line on the screen) output from the video signal processing circuit 25 in a focused state. As shown in FIG. 6, the luminance signal BS in a focused state shows a sharp change. FIG. 7 shows an output obtained by processing the luminance signal BS shown in FIG. Further, FIG. 8 shows a contrast signal CS obtained by processing the output of the high pass filter 31 shown in FIG.

  On the other hand, FIG. 9 shows an example of the luminance signal BS in an out-of-focus state, FIG. 10 shows the output of the high-pass filter 31 corresponding to FIG. 9, and FIG. 11 shows the contrast signal CS corresponding to FIG. As shown in FIG. 9, since the image is blurred in the out-of-focus state, the luminance signal shows a gradual change. Here, in the focused state, the contrast of the acquired image is high, that is, as shown in FIG. 8, the amplitude of the contrast signal CS output from the detection circuit 32 is large. On the other hand, in a state where the focus is not achieved, the contrast of the acquired image is small, that is, as shown in FIG. 11, the amplitude of the contrast signal CS is relatively small compared to FIG. Such a contrast signal CS is AD-converted by the AD converter 33 and input to the CPU 22. The CPU 22 sets the AD-converted contrast signal CS in the image output to the monitor 14 for each field. It is possible to calculate an average obtained by adding the values in the focus area FA as a contrast value, and evaluate whether the contrast in the focus area FA is high, that is, whether the focus is in an optimum state based on the contrast value. be able to.

  An operation interface 35 is connected to the CPU 22 via a bus 34, and a joystick 36 that is an operation unit is connected to the operation interface 35. As shown in FIG. 12, the center position FA1 of the focus area FA can be freely adjusted in the image P output to the monitor 14 by operating the joystick 36. The operation with the joystick 36 is input to the CPU 22 as position information of the center position FA1 of the focus area FA, and is also input to the focus area overlay circuit 38 connected to the operation interface 35, on the monitor 14 together with the image P by the video signal VS. Is displayed. For this reason, the observer can adjust the position of the focus area FA on the image while checking the monitor 14 with the joystick 36.

  In addition, a ROM 28 and a RAM 29 are connected to the CPU 22 via a bus 34. The ROM 28 is written with a program for performing autofocus, which will be described later, and measuring the position and distance of the subject. The RAM 29 defines a buffer area, luminance signal data, and contrast value data. The luminance signal and contrast value are input from the CPU 22 and are written as needed. Further, the CPU 22 determines the presence / absence of an image change based on the luminance signal and the contrast value, and drives the electromagnet drive circuit 27 based on the determination result to adjust the position of the image sensor 13. Details of the determination and control method by the CPU 22 will be described later.

  The electromagnet drive circuit 27 which is a voltage application means can apply an alternating voltage and a direct current voltage whose magnitude is variable to the coil 21 of the image sensor moving means 16 in a superimposed manner. The digital signal output by the CPU 22 based on the determination result is DA-converted by the DA converter 37, and the electromagnet driving circuit 27 applies a DC voltage having a magnitude set based on the DA-converted signal to a predetermined value. The voltage is applied to the coil 21 while being superimposed on an AC voltage having an amplitude and amplitude. For example, an alternating voltage having a frequency of about 100 kHz is applied. When the DC voltage is set to 0 V, the voltage applied by the electromagnet driving circuit 27 is only an AC voltage, and the current flowing through the coil 21 is a sine wave current that is symmetrical with respect to the positive and negative as shown in FIG. For this reason, the magnetic field generated by the current flowing through the coil 21 has the same magnitude and reverses the direction alternately. The shaft body is caused by the interaction with the magnetic field by the cylindrical body 18 which is a permanent magnet. The force having the direction alternately reversed along the optical axis L11 is applied to 17 in synchronization with the alternating current. For this reason, as shown in FIG. 4, the shaft body 17 is in a stationary state in which the forces acting alternately in reverse are balanced at a position where the base end 17 a is an intermediate position of the cylindrical body 18.

  On the other hand, for example, when the DC voltage has a positive value and a predetermined magnitude, the voltage applied by the electromagnet drive circuit 27 is obtained by superimposing the DC voltage on the AC voltage. That is, as shown in FIG. 14, the current flowing through the coil 21 is obtained by shifting the alternating current by a bias value + A that is a current value corresponding to the direct current voltage, and the positive current is compared with the negative current, The absolute value of the current increases, and the flowing time increases. For this reason, as shown in FIG. 15, if the polarity of the base end 17 a of the shaft body 17 when a positive current is passed through the coil 21 is an N pole, the shaft body 17 positioned at the intermediate position of the cylinder body 18 A force directed toward the base end 18 b is more exerted on the base end 17 a than a force directed toward the distal end 18 a of the cylindrical body 18, so that the shaft body 17 has a base end 17 a that is located at an intermediate position of the cylindrical body 18. Also, the balance is brought into a stationary state at a position approaching the base end 18b. Further, when the bias value is set to −A as shown in FIG. 16, conversely, a large force is exerted on the shaft body 17 toward the tip end 18 a side of the cylindrical body 18, and as a result, as shown in FIG. 17, The shaft body 17 is balanced and stationary at a position where the base end 17a is closer to the distal end 18a side than the intermediate position of the cylindrical body 18. In each state, the direction of the force acting on the shaft body 17 is alternately reversed according to the period of the alternating current. However, since the period of the alternating current is, for example, a high frequency of 100 kHz, The shaft body 17 is not mechanically vibrated along the guide 20, so that the image sensor 13 can be kept stationary at a predetermined position.

  FIG. 18 shows the relationship between the position of the base end 17a of the shaft body 17 and the bias value. In FIG. 18, bias values A1 to A5 and image sensor positions B1 to B5 indicate bias values and corresponding image sensor positions in a focus adjustment example described later. As shown in FIG. 18, by changing the bias value, the position of the base end 17 a of the shaft body 17, that is, the position of the image sensor 13 can be controlled by the sign and size. On the other hand, when the absolute value of the bias value is increased beyond a certain level, the position of the image sensor 13 does not change depending on the amplitude of the alternating current and the range in the direction of the optical axis L11 where the cylindrical body 18 is disposed.

  Here, as shown in FIG. 19, as the objective lens 11 of the imaging apparatus 10 used in the endoscope apparatus 1 as in the present embodiment, the distance from the principal point 11 a of the objective lens 11 to the focal point 11 b (hereinafter referred to as the objective lens 11). And a focal length f) of about 2 mm is selected. Further, the focal length f of the objective lens 11, the separation distance L from the principal point 11a of the objective lens 11 to the light receiving surface 13a of the image sensor 13, and the direction of the optical axis L11 from the principal point 11a of the objective lens 11 to the subject S There is a relationship shown in the following <Equation 4> between the distance Z and the distance Z.

  Since the endoscope apparatus 1 inserts the insertion portion 2 into a narrowed portion such as a cavity and observes the subject S located inside the stenosis portion, the endoscope device 1 is subject to observation from the principal point 11a of the objective lens 11. The distance Z to the specimen S is about 5 mm to 500 mm. For example, when the focal distance f = 2 mm and the distance Z to the subject S = 5 mm, the separation distance of the image sensor 13 is L = 3.333 mm. Further, if the distance Z to the subject S is 500 mm, the separation distance of the image sensor 13 is L = 2.008 mm. That is, in order to set the position of the imaging device 13 to the focus position in a focused state with respect to the subject S, L = 2 to 4 mm based on the principal point 11a of the objective lens 11 from <Equation 4>. What is necessary is just to be able to adjust in the movable range of about 2 mm. Therefore, if the length of the cylindrical body 18 is set to a length that allows the shaft body 17 to move within a range of about 2 mm, the bias value is designated and the position of the image sensor 13 is adjusted to be in focus. It is possible.

  Next, details of control by the CPU 22 and operations of the imaging apparatus 10 and the endoscope apparatus 1 will be described. 20 and 21 show a control flow by the CPU 22. First, as shown in FIG. 20, in the endoscope apparatus 1, the imaging apparatus 10 is turned on (step S <b> 1), and the insertion unit 2 is inserted from the distal end toward the subject. At this time, the image sensor 13 receives an image by light incident on the objective lens 11 at the distal end of the insertion portion 2, and the photoelectric conversion output PO is input to the video signal processing circuit 25. Then, an image is displayed on the monitor 14 by the video signal VS output from the video signal processing circuit 25. At the same time as the image is displayed on the monitor 14, the luminance signal BS corresponding to the video signal VS and the contrast signal CS are input to the CPU 22 (step S2). At this time, since the pixel clock signal CK, the horizontal synchronization signal HD, and the vertical synchronization signal VD are also input to the CPU 22, the luminance signal BS and the contrast signal CS input to the CPU 22 are any images that are repeatedly acquired. It is associated with which position information in. Then, the input luminance signal BS for one field of the image and the contrast value calculated from the input contrast signal CS are written in the buffer area of the RAM 29 (step S3).

  Next, the CPU 22 extracts the luminance signal BS acquired in the previous field from the RAM 29, calculates a correlation value with the luminance signal BS acquired in the current field (step S4), and calculates the current value based on the calculated correlation value. It is determined whether or not there is a correlation between the luminance signal BS of the field and the luminance signal BS of the previous field (step S5). While the insertion unit 2 is being inserted toward the subject, the image received by the image sensor 13 is constantly changing, so the CPU 22 repeatedly determines that there is no correlation in step S5. For this reason, as long as the image changes, the autofocus operation is not started. That is, since the focus is substantially constant even if it is not in an optimal state, the image does not change, and the observer preferably checks the image displayed on the monitor 14 while The insertion section 2 can be inserted until the objective lens 11 is close to the subject.

  Next, for example, when the subject is confirmed in the image displayed on the monitor 14, the observer stops the insertion of the insertion unit 2, so that the image received by the image sensor 13 is not changed. Therefore, in step S5 shown in FIG. 20, based on the correlation value calculated in step S4, the CPU 22 determines the luminance signal BS of the image acquired in the current field and the luminance of the image acquired in the previous field. It is determined that there is a correlation with the signal BS. Next, the CPU 22 further extracts the luminance signal BS acquired in the previous field from the RAM 29 and calculates a correlation value with the luminance signal BS of the previous field (step S6). Then, the CPU 22 determines whether or not there is a correlation between the luminance signal BS of the previous field and the luminance signal BS of the previous field based on the calculated correlation value (step S7). When it is determined that there is no correlation, for example, when the insertion of the insertion unit 2 is stopped immediately before the change in the image is not seen, the autofocus operation is started (step S8). For this reason, the focus is adjusted at the position where the distal end of the insertion portion 2 is stopped, and the subject can be observed with a high-resolution image. On the other hand, when it is determined that there is a correlation, for example, when the insertion of the insertion unit 2 is continuously stopped and there is no image change, the operation from step S2 is repeated without starting the autofocus operation. Do. For this reason, when the subject is observed with the image displayed on the monitor 14 after the insertion of the insertion unit 2 is stopped, the auto-focus operation is started unnecessarily, thereby reducing the resolution of the image. Can be prevented from becoming difficult to observe.

  Next, details of the autofocus operation will be described. That is, when the CPU 22 determines in step S8 in FIG. 20 that the autofocus operation is started, as shown in FIG. 21, the CPU 22 sets the increase / decrease amount preset and stored from the RAM 29 as the increase / decrease amount of the bias value− ΔA1 is read (step S9). At this stage, the image pickup device when the bias value, which is the current value flowing through the coil 21 of the image pickup device moving means 16 by the electromagnet drive circuit 27 based on the signal output from the CPU 22, is A1 and the bias value A1. Assume that the position 13 is B1, and the contrast value in the focus area FA calculated by the contrast signal CS input to the CPU 22 at that time is 34. Next, the CPU 22 adds the increase / decrease amount −ΔA1 read in step S9 to the current bias value A1, and inputs a signal to the electromagnet driving circuit 27 so that the resulting bias value A2 is obtained. 27, a current is passed through the coil 21 with the bias value A2 (step S10). For this reason, as shown in FIG. 18, the position of the image sensor 13 moves to a position B2 corresponding to the bias value A2. Imaging by the image sensor 13 is continuously performed, and the contrast signal CS after the image sensor 13 has moved to the position B2 is input to the CPU 22 (step S11). Then, the CPU 22 calculates a contrast value in the focus area (step S12) and writes it in the RAM 29 (step S13). Here, it is assumed that the contrast value is 25 when the bias value is A2 (position B2 of the image sensor 13).

  Next, the CPU 22 determines whether or not the contrast value calculated this time is larger than the contrast value calculated last time (step S14). Since the contrast value calculated this time is 25 and the contrast value calculated last time is 34, the contrast value is decreased, and the currently set increase / decrease amount −ΔA1 is inverted and the absolute value is reversed. The amount of increase / decrease is set to + A2 (step 15), and the operation from step S10 is performed again. Assume that the contrast value at the bias value A3 obtained by adding the increase / decrease amount + ΔA2 is 40. From this result, in step S14, the CPU 22 calculates the difference between the current contrast value and the previous contrast value, assuming that the contrast value has increased. Then, it is determined whether this difference is equal to or less than a preset boundary value, and the operations from step 10 are repeated until the difference is equal to or less than the boundary value. In this embodiment, for example, the boundary value is 2.

  18, 22 and 23 show an example of the result of the autofocus operation. That is, as described above, the contrast value is 34 when the position of the image sensor 13 is B1 (bias value A1), the contrast value is 25 when the position of the image sensor 13 is B2 (bias value A2), and the steps The contrast value is 40 when 15 is performed to obtain the position B3 (bias value A3) of the image sensor 13. Since the difference between the current and previous contrast values is | 40−25 | = 15, which is larger than the boundary value, the same increase / decrease amount Δ + A2 is added to set the bias value to A4. For this reason, the image sensor 13 has a position corresponding to the bias value A4 as B4, and as a result, the contrast value is 34 and again shows a value smaller than the previous contrast value.

  For this reason, in step S15 again, the sign is inverted and the absolute value is reset to an increase / decrease amount halved, and the bias value A5 is added. Then, the image sensor 13 moves to a position B5 corresponding to the bias value A5, and the contrast value is 41. The difference from the previous contrast value is | 41−34 | = 7, which is still larger than 2 which is the boundary value. Therefore, the determination in step S16 is NO. Since one field of the image is as short as 1 / 60th of a second, the time up to this point has not yet elapsed in one second, so the determination in step S18 is NO, and the process returns to step S10. A similar increase / decrease amount Δ + A2 is added to obtain a bias value A6. For this reason, the image sensor 13 is at a position B6 corresponding to the bias value A6, and the contrast value is 40. The difference from the contrast value is | 40−41 | = 1, indicating a boundary value of 2 or less. Thus, by repeatedly changing the position of the image sensor 13 and comparing the contrast values, the measured contrast value becomes substantially equal to the theoretical maximum value, that is, the position of the image sensor 13 is optimally focused. It is possible to set the focus position so as to achieve a correct state. If the difference between the current contrast value and the previous contrast value is less than or equal to the boundary value, the autofocus operation is completed assuming that the focus is in an optimum state based on the determination in step S16. (Step S17).

  Here, in the above description, the operation for changing the bias value is performed five times. In a normal case, the focus can be adjusted by repeating such an operation several times to ten times. In the above description, it is assumed that one adjustment is performed in two fields, that is, one field for calculating the contrast value, one field for moving the image pickup device 13, and one image displayed on the monitor 14 is 1. Assume that there are 60 fields per second. In this case, a maximum of 30 adjustments can be performed per second, and the focus can be surely brought into an optimum state within one second.

  In the present embodiment, if it is determined in step S16 shown in FIG. 21 that the current contrast value is larger than the boundary value, the CPU 22 starts the autofocus operation before proceeding to step S10. It is determined whether more than one second has elapsed (step S18). If it is within one second, the process proceeds to step S10 and the focus is adjusted again. On the other hand, if one second or more has elapsed, the process proceeds to step S17 to forcibly complete the autofocus operation. For this reason, it is possible to prevent the autofocus operation from being repeated indefinitely when the insertion portion 2 is moved after the autofocus operation is started and the distance between the subject and the objective lens 11 is changed.

  Next, a method for measuring the three-dimensional coordinates of the subject displayed as an image by the CPU 22 of the control unit 15 and a method for measuring the distance between points will be described. The ROM 28 stores a program for calculating according to the following formulas <Equation 5>, <Equation 6>, and <Equation 7> based on the relationship shown in <Equation 4>. Then, the CPU 22 can calculate the actual three-dimensional coordinates (X, Y, Z) of the predetermined position of the subject with the principal point 11a of the objective lens 11 as the origin, using these mathematical expressions. Here, symbol f is the focal length of the objective lens 11, and symbol L is from the principal point 11a of the objective lens 11 to the image receiving surface 13a of the image sensor 13 when the focus is in an optimum state by the autofocus operation. (See FIG. 19). Also, as shown in FIG. 24, two axes x-axis and y-axis orthogonal to each other are defined on the image P displayed on the monitor 14, and the symbols Mx and My are designated with the center P1 of the image P as the origin. The two-dimensional coordinates of the center position FA1 of the focused area FA are shown. Reference sign Z is the coordinate in the direction of the optical axis L11 with the principal point 11a of the objective lens 11 as the origin, and reference signs X and Y are the principal point 11a of the objective lens 11 as the origin and the x axis on the image P and The coordinates in the direction corresponding to the y-axis are shown.

  That is, if the observer operates the joystick 36 and designates S1, which is one point of the subject S, on the image P displayed on the monitor 14, as the center position FA1 of the focus area FA, the CPU 22 The autofocus operation shown in FIG. 21 is started to bring the focus into an optimum state. Then, the CPU 22 measures the separation distance L from the principal point 11a of the objective lens 11 to the image receiving surface 13a of the image sensor 13 at the position of the image sensor 13 at this time. The separation distance L can be obtained by using the position B6 of the image sensor 13 at the completion of the autofocus operation and adjusting the fixed dimension based on the structure of the endoscope. Furthermore, on the image P, two-dimensional coordinates Mx and My are calculated. Then, the CPU 22 inputs the focal length f, the separation distance L, and the two-dimensional coordinates Mx and My into <Equation 5>, <Equation 6>, and <Equation 7> stored in the ROM 28. The three-dimensional coordinates (X, Y, Z) with the principal point 11a of the objective lens 11 at the point S1 of the subject S as the origin can be calculated. When the observer further specifies the next one point S2, the three-dimensional coordinates (X, Y, Z) are also calculated for the point S2, and further, the calculation results of these three-dimensional coordinates (X, Y, Z) are calculated. Thus, the distance between the two points S1 and S2 can be calculated. Similarly, as shown in FIG. 25, when a plurality of points are designated, for example, when a total of four points S3, S4, S5, and S6 are designated successively, three-dimensional coordinates (X, Y, It is also possible to calculate Z) and measure the extension of the path from point S3 to point S6 via points S4 and S5.

  As described above, according to the imaging device 10 of the present embodiment and the endoscope device 1 including the imaging device 10, the image change is quantitatively performed based on the luminance signal of the image acquired by the imaging device 13. It is possible to start the autofocus operation only when there is no change in the image. For this reason, when the distance between the subject and the objective lens 11 is changed, such as when the insertion unit 2 is moved, the focus is not optimal, but the subject is preferably searched in a stable state. Alternatively, the distance between the objective lens 11 and the subject can be adjusted. Since the focus can be adjusted to an optimal state when there is no change in the image, a desired subject can be suitably observed with a high-resolution image. In the present embodiment, the center position FA1 of the focus area FA can be freely adjusted with the joystick 36, so that the focus can be adjusted to an optimum state at a desired position in the image. Can be observed.

  Further, the actual three-dimensional coordinates and the point-to-point distance of the subject S can be measured by the above autofocus operation and the designation of the center position FA1 of the focus area FA by the joystick 36. Therefore, not only can the subject be observed in detail with a high-resolution image, but also quantitative evaluation can be performed.

  In the imaging device moving means 16, the shaft body 17 is an electromagnet and the cylinder 18 is a permanent magnet. However, the present invention is not limited to this, and the shaft body 17 is a permanent magnet and the cylinder 18 is an electromagnet. Also good. Moreover, although the image pick-up element moving means 16 was based on the interaction of the magnetic field of an electromagnet and a permanent magnet, it is not restricted to this. For example, the imaging element moving means may include a piezoelectric element to which the imaging element is fixed. In this case, by controlling the voltage applied to the piezoelectric element, the imaging element can be moved within a range in which the piezoelectric element can be displaced.

  In the present embodiment, the endoscope apparatus 1 is a so-called direct view type in which the objective lens 11 is provided on the distal end surface of the insertion portion 2, but is not limited to this, and the endoscope device 1 is provided on the side surface of the insertion portion 2. A side view type in which the objective lens 11 is provided may be used. Furthermore, although the imaging apparatus 10 has been described as one configuration of the endoscope apparatus 1, the imaging apparatus 10 is not limited to this, and can be used by being incorporated in another apparatus, or may be used as a single unit. good.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

1 is an overall configuration diagram showing an endoscope apparatus according to an embodiment of the present invention. It is a block diagram which shows the imaging device of the endoscope apparatus of embodiment of this invention. It is a front view of the insertion part front-end | tip of the endoscope apparatus of embodiment of this invention. It is sectional drawing of the insertion part front-end | tip of the endoscope apparatus of embodiment of this invention. It is a perspective view which shows the detail of an image pick-up element moving means in the imaging device of embodiment of this invention. 5 is a graph illustrating an example of a luminance signal output from a video signal processing circuit in the imaging apparatus according to the embodiment of the present invention. 6 is a graph illustrating an example of a signal output from a high-pass filter in the imaging apparatus according to the embodiment of the present invention. 5 is a graph illustrating an example of a contrast signal output from a detection circuit in the imaging apparatus according to the embodiment of the present invention. 6 is a graph illustrating another example of a luminance signal output from a video signal processing circuit in the imaging apparatus according to the embodiment of the present invention. 6 is a graph illustrating another example of a signal output from a high-pass filter in the imaging device according to the embodiment of the present invention. 6 is a graph illustrating another example of a contrast signal output from a detection circuit in the imaging apparatus according to the embodiment of the present invention. It is explanatory drawing which shows an example of the image displayed on a monitor in the imaging device of embodiment of this invention. 4 is a graph illustrating a first example of a current waveform output from an electromagnet drive circuit in the imaging apparatus according to the embodiment of the present invention. 6 is a graph showing a second example of a current waveform output from an electromagnet drive circuit in the imaging apparatus according to the embodiment of the present invention. It is explanatory drawing which shows operation | movement of an image pick-up element moving means in the case where the current waveform output from an electromagnet drive circuit is made into the 2nd example. It is a graph which shows the 3rd example of the current waveform output from an electromagnet drive circuit in the imaging device of embodiment of this invention. It is explanatory drawing which shows operation | movement of an image pick-up element moving means in the case where the current waveform output from an electromagnet drive circuit is made into the 3rd example. 6 is a graph showing the relationship between the bias value and the position of the image sensor in the image sensor moving means of the image pickup apparatus according to the embodiment of the present invention. It is explanatory drawing which shows the relationship between an objective lens, an image pick-up element, and a test subject. It is a flowchart at the time of performing an autofocus operation | movement in the imaging device of embodiment of this invention. It is a flowchart at the time of performing an autofocus operation | movement in the imaging device of embodiment of this invention. 6 is a graph showing the relationship between the position of the image sensor and the detected contrast value when performing an autofocus operation in the imaging apparatus according to the embodiment of the present invention. 6 is a table showing a relationship among a bias value when performing an autofocus operation, a position of an image sensor, and a detected contrast value in the imaging apparatus according to the embodiment of the present invention. It is explanatory drawing at the time of measuring the three-dimensional coordinate of a subject, and the distance between points in the imaging device of embodiment of this invention. It is explanatory drawing at the time of measuring the three-dimensional coordinate of a subject, and the distance between points in the imaging device of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Endoscope apparatus 2 Insertion part 10 Imaging device 11 Objective lens 11a Main point 13 Imaging element 15 Control unit 16 Imaging element moving means 17 Shaft body 17a Base end 18 Cylindrical body 22 CPU (control part)
25 Video signal processing circuit (luminance detection means)
26 Contrast value detection means 27 Electromagnet drive circuit (voltage application means)
36 Joystick (operation unit)
f Focal length of objective lens FA Focus area FA1 Center position L Separation distance L11 Optical axis Mx, My Two-dimensional coordinates on screen P Image P1 Center X, Y, Z Three-dimensional coordinates

Claims (9)

An objective lens;
An image sensor that is disposed coaxially with the optical axis of the objective lens, receives incident light collected by the objective lens, and repeatedly acquires images;
An image sensor moving means for moving the image sensor on the optical axis of the objective lens;
When the image acquired this time with the image sensor is compared with the image acquired last time and the image has not changed before and after, the position of the image sensor is changed to the focus position by the image sensor moving means. a control unit for adjusting so that,
A focus area is preset as a partial range in the image acquired by the image sensor, and an operation unit capable of adjusting a center position of the focus area in the image;
Equipped with a,
The control unit is
Contrast value detecting means for detecting a contrast value of the image;
The position of the image sensor is adjusted by the image sensor moving means to a position where the contrast value of the image detected by the contrast value detecting means is maximized, and based on the contrast value in the focus area A control unit for adjusting the position of the image sensor;
With
When the focus area is designated by the operation unit, the control unit of the control unit determines the position of the imaging element when the contrast value is maximized and the center position of the focus area on the image. Based on the measured position of the image sensor and the center position of the focus area on the screen, the actual three-dimensional coordinates designated as the center position of the focus area can be calculated.
The control unit compares the image acquired this time with the image acquired last time, and determines whether there is a change from the image acquired last time of the image acquired this time based on a luminance signal in each image If the image has not changed before and after, the image acquired last time is compared with the image acquired last time, and the image acquired last time by the luminance signal in each image is compared. The presence / absence of a change from the acquired image is determined, and when the image has changed in comparison with the previous image, the position of the image pickup device is set to the focus position by the image pickup device moving means. To adjust
An imaging apparatus characterized by that . The imaging device according to claim 1 ,
The control unit includes luminance detection means for detecting the luminance of the image;
A control unit that determines whether or not the image has changed based on whether or not the luminance of the image detected by the luminance detection unit has a correlation, and adjusts the position of the imaging element by the imaging element moving unit An imaging apparatus comprising: In the imaging device according to claim 1 or 2,
The control unit of the control unit is arranged on the image with the distance L from the principal point of the objective lens at the position of the imaging element and the center position of the image at the center position of the focus area as the origin. Two-dimensional coordinates Mx, My are measured, and the three-dimensional coordinates X, Y, Z of the center position of the designated focus area with the principal point of the objective lens as the origin are expressed as <Equation 1>, < An image pickup apparatus that can be calculated from the calculation formulas (2) and (3), where the symbol f is the focal length of the objective lens.

In the imaging device according to any one of claims 1 to 3,
The operation unit can specify a plurality of the center positions of the focus area in the image acquired by the imaging device,
The control unit of the control unit can calculate an actual point-to-point distance between the center positions of the focus areas based on the calculated three-dimensional coordinates of the center positions of the focus areas. An imaging apparatus characterized by that. In the imaging device according to any one of claims 1 to 4 ,
The image pickup device moving means is provided so as to be able to advance and retreat on the same axis as the optical axis of the objective lens, and is provided on a shaft body in which the image pickup device is disposed at a distal end, and on a base end side outer periphery of the shaft body. A cylindrical body, and either one of the shaft body and the cylindrical body is a permanent magnet that forms a magnetic field substantially parallel to the optical axis of the objective lens, and the shaft body and the cylindrical body The other is an electromagnet capable of forming a magnetic field substantially parallel to the optical axis of the objective lens. The imaging apparatus according to claim 5 ,
The image pickup apparatus, wherein the control unit includes a voltage applying unit capable of superimposing an AC voltage and a DC voltage having a variable magnitude on the electromagnet. The imaging device according to any one of claims 1 to 6 ,
An endoscope apparatus comprising: the objective lens of the imaging apparatus on a distal end side; and an insertion portion that can be inserted into a subject. Focus adjustment of an image pickup apparatus including an objective lens and an image pickup element that is arranged so as to be movable back and forth on the same axis as the optical axis of the objective lens and that receives incident light collected by the objective lens and repeatedly acquires an image A method,
A focus area is set in advance as a partial range of the image acquired by the image sensor,
Adjust the center position of the focus area in the image,
Detecting a contrast value in the focus area of the image acquired by the imaging device;
Compare the image acquired this time with the image sensor and the image acquired last time, determine the presence or absence of a change from the previously acquired image of the image acquired this time by the luminance signal in each image, When the image does not change back and forth, the image sensor is moved on the optical axis of the objective lens, and the position of the image sensor is adjusted to be a focus position ,
When the image acquired this time with the imaging device is compared with the image acquired last time, and the image has not changed before and after, the image acquired last time and the image acquired before Compared with the image, the presence or absence of a change from the previously acquired image is determined based on the luminance signal in each image, and the image has changed in comparison with the previous image. In this case, the position where the contrast value is maximized is measured based on the contrast value in the focus area, and based on the measured position of the imaging element and the center position of the focus area on the screen. The actual three-dimensional coordinates designated as the center position of the focus area are calculated, and the position of the image sensor is adjusted to be the focus position. And a focus adjusting method of an imaging apparatus according to claim <br/> adjusting the position of the imaging element. The focus adjustment method for an imaging apparatus according to claim 8,
The brightness of each image repeatedly acquired by the image sensor is detected, and the position of the image sensor is adjusted by determining whether or not the image has changed based on whether the brightness of the image has a correlation. A focus adjustment method for an image pickup apparatus.

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